1. Field of the Invention:
This invention relates in general to retrieving tools for retrieving a packoff from a casing hanger landed in a subsea well, particularly a metal seal packoff.
2. Description of the Prior Art:
In the subsea wells of the type concerned herein, a wellhead will be located at the subsea floor. One or more strings of casing are supported at the wellhead, each by a casing hanger. A packoff seals the annular space surrounding each casing hanger.
Occasionally, a packoff may need to be retrieved to the surface. A floating vessel located at the surface will connect to the wellhead by means of a riser. A retrieving tool is lowered on a drill string. The retrieving tool has a means for securing to the packoff. Then the drill string is pulled upward to release the packoff.
While this is satisfactory for elastomeric seal packoffs, it is more difficult to achieve with a metal packoff. Elastomeric packoffs are set at much lower forces than metal packoffs. It may be difficult to achieve sufficient pulling force with the drill string to pull a metal packoff loose.